sagging curl on front end loader

[merrickvilleguy]

Have plenty of power (can curl a bucket load of top soil and moves fast), however with a load in the bucket, or not, it will sag (2 mins itll sag about 1/4"). The frame doesn't sag at all, just the bucket curl. I have performed the test with idle and 1500rpm to see if there is a difference, there isn't.

Am I being nuts here or do I have a problem ?

 

[beenthere]

I don't think that little movement will be out of the ordinary, or unacceptable movement.
It is a nuisance for sure, but prolly not something you want to chase after. IMO.

 

[merrickvilleguy]

Ok keen, it was just one of the things I noticed this week. I had knocked one of the lines (the uncoloured line on the dl120) last week so was concerned they were related.

 

[J_J]

If you curl your bucket up and leave the lift arms in the air, will the curl dump all the way, and will the lift arms fall in 24 hrs?

The rate you suggested is about 7.5 in per hour.

How old is your system.

There is an acceptable rate drop, but your dealer would know what it is, and probably will not do anything about it unless is is dropping beyond the acceptable rate, and you complain enough.

 

[AKKAMAAN]

If you curl cyl's are hooked up like this to the bucket (curl up on retract), you most likely have a failing/leaking piston seal in one of the cylinders

 

[J_J]

Even if the cyl leaked, would the cyl leak all the way down. I would think the pressure on both sides of the cyl would equalize.

You might try swapping the hoses for the lift and curl circuits and see if there is any difference.

 

[merrickvilleguy]

well its a bit late to do a full test to see how far it'd drop, but I just did a 10 minute test.

put the bottom pin at 18", it stayed there for the entire test.
the amount of cylinder showing was 1" at full curl, after 10 mins was 2.75" (this moved the edge of the bucket from 31" to 19.5")
was running at 1500rpm throughout the test

 

[AKKAMAAN]

no pressure equalization when cyl drift out (leak from rod side into capped side), just some low vacuum on capped side.

Pressure equalization occcurs when it tries to leak from capped side into rod side. Capped side volume wont fit into capped side, due to the rod volume....

 

[J_J]

Does this have any credibility?

Hydraulic Cylinder Myth Exploded

 

[AKKAMAAN]

Does this have any credibility?

Hydraulic Cylinder Myth Exploded

100% credability! Did I say anything else??

 

[TTTTTT]

Heres a recent thread that may help as well

http://www.tractorbynet.com/forums/hydraulics/207979-help-curl-cylinders-acting-up.html

Dave

 

[merrickvilleguy]

Spoke with the dealer this morning, and he suggested yanking the cylinders off and replacing em (I'm 2 weeks outside warranty and they are still going to eat it) ... so will see if that covers things ... or if its the valves that are shot ?

 

[AKKAMAAN]

Spoke with the dealer this morning, and he suggested yanking the cylinders off and replacing em (I'm 2 weeks outside warranty and they are still going to eat it) ... so will see if that covers things ... or if its the valves that are shot ?

(2 mins itll sag about 1/4")

1/4" drift on cylinder or 1/4" drift on the front end edge of the bucket??

If we assume bore 2" and rod 1", a 1/4" drift on cylinder (cyl extends on drift, flow from rod end) is about 0.59cui or 12.9cc. That will make a 6.5 cc drift per minut, which is a little more than normal for a spool valve leakage, especially if drift is under low pressure.

Spool valves always leak, and they are designed to do that. A "normal" spool leakage number is around 3 cc/min @ 1500 psi. Spools normally do not wear like a piston seal, and leakage can be expected to stay almost the same over almost the entire lifetime of the equipment unit.

The drift can also be caused by a leak between cylinder and spool valve, if there is a work port PRV installed.

How many total hours of operation do you have on your FEL??

I still think there is a good chance, that replacing the cyl's will fix the problem. Please keep us updated.

 

[merrickvilleguy]

the 1/4" drop was for the level gauge, I later did a 10 minute measure of the cylinder of 1.75" at 1500rpm and no load (this amounted to a lot at the edge of the bucket)

edit: just under 200 hrs on the tractor (1yr old) and most of that the loader was on, probably 1/4 of the hrs are loader work

 

[J_J]

You seem to only be talking about when the engine is running.

What is the rate of fall with the tractor not running. The valve could be leaking fluid into the base end.

Raise the lift arms up fully, and curl back the bucket and shut off engine, then tell us what the leak down is.

 

[AKKAMAAN]

First of all, the engine rpm's should not have any noticeable impact on the cylinder drift. There is of course a few psi variation of back pressure in the return line, at different rpm's.

Lifting the FEL all the way up, and the curl all the way up/back, will certainly change the leverage structure on the curl cylinders and the bucket point of gravity relative to the bucket pivot point. In a fully raised position like that we can assume a less pressure in the curl cylinder and therefore less drift.

This FEL lift/bucket curl drift is for sure a PITA and a hazard when travelling on the road, especially with a heavy load in the bucket, or on the forks if such are used.

 

[J_J]

Are you sure that the spools can't leak and add some fluid to the base end of the cyl and aid to curling the bucket down?

If a valve lever does not reset to neutral, what would happen?

 

[J_J]

If you want positive confirmation that the seals are leaking, add some shut off valves to the curl cyl, grab a load and lift somewhat, and then shut off both valves. If the bucket curls down, you will have your answer.

 

[LD1]

Just swap out the lift and curl hoses at the valve.

Keep in mind that the functions will be backwards.

If the problem moves to the lift, it is the valve.

If the problem stays the same, it is the cylinders.

 

[merrickvilleguy]

Just swap out the lift and curl hoses at the valve.

Keep in mind that the functions will be backwards.

If the problem moves to the lift, it is the valve.

If the problem stays the same, it is the cylinders.

actually thought of this at work today and tried it out at home ... sure enough the curl still sagged ... so now I have to take the curl cylinders off and get the seals fixed